Mail group unrelated email in one conversation


macrumors 6502
Original poster
May 30, 2011
I have Yosemite 10.10.2. Since updating to Yosemite 10.10, the mail starts to group unrelated emails together in one conversation. Those emails have different subject, different recipients and are totally unrelated. Most of the grouping is correct but some of the message appears to be incorrectly grouped. I have tried rebuild mailbox, deleting the Envelop file, deleting account and add back, delete all mails and reimport the mailbox. None of them help. Any idea how I can fix this?


macrumors newbie
Apr 20, 2010
Having the same issue. It is really anonying, since I use for work.

I have posted this bug to Apple more than 2 month ago. It is still unfixed in 10.10.2. I am very curious if most people don't have this issue?


macrumors member
Sep 9, 2005
I also have this issue, it was tolerable before but now I'm starting to get huge email threads with dozens and even hundreds of completely unrelated emails stuck together.

This is clearly something that went wrong in Yosemite, as there was never any problem in Mavericks.

There are a number of threads about the issue on Apple's official boards:

Lots of things people have been doing to try and fix it, like re-indexing the mailbox, deleting and then adding the account again...etc. Nothing seems to be a silver bullet though.

Hopefully Apple will fix this bug in the next update.


macrumors 65816
May 1, 2009
same here. super frustrating.

there is no rhyme or reason to it.

When you expand the group, it shows the correct subjects - but still groups them. I even have one case right now where it's got the wrong name up in the main window, but the correct message (and name) down below in the message area.

what on earth went wrong with mac mail?